Means for offset printing



H. J. LUEHRS BA S FOR OFFSET PRINTING March 7, 1950 Filed June 21, 1946 2 Sheets-Sheet 1 Zrne March 7, 1950 H. J. LUEHRS 2,499,871

MEANS FOR OFFSET PRINTING 2 Sheets-Sheet 2 Filed June 21, 1946 Patented Mar. 7, 1950 UNlTED .STATES PATENT OFFICE- MEANS FOR OFFSET PRINTING Hans J. Luehrs, Westerly, R. I., assignor to C.

Cottrell & Sons Company, Westerly, R. I., corporation of Delaware Application June 21, 1946, Serial No. 678,426

2 Claims. I

In web offset rotary printing presses designed especially for textile printing it has been customary to employ a dampening unit for each printing cylinder so that the moisture was applied directly to the surface of each of the printing cylinders. This method, while satisfactory for printing on paper, parchment and cellophane. tends to produce poor contours and incomplete color separation of the design on textiles, due to the heavy film of ink necessary for coverage and its required chemical composition, suitable for this material. Furthermore, these presses were necessarily complex because of the number of dampening units employed and also were expensive to build.

My invention consists in novel means for and method of web perfecting ofiset printing in which the moistening agent is applied directly to the surface of each of two coacting offset cylinders between which the traveling web is passed. the

single dampening unit for each offset cylinder together with any desired number of printing cylinders for each offset cylinder ensuring sharp contours and perfect color separation as well as materially simplifying the construction of the press and reducing its cost.

A practical embodiment of my invention is represented in the accompanying drawings in which Fig. 1 represents in diagram a web perfecting offset double two-color rotary printing press;

Fig. 2 represents a somewhat enlarged diagram showing the dampening cylinders as having raised moisture carrying surfaces and the printing cylinders as having raised ink carrying surfaces coacting therewith;

Fig. 3 represents a detail view of one of the dampening cylinders taken in the plane of the line III of Fig. 2, looking in the direction of the arrow;

Fig. 4 represents a similar view of the other dampening cylinder taken in the plane of the line Fig. 8 represents a similar view of the other second printing cylinder taken in the plane of the line VIII of Fig. 2, looking in the direction of the arrow.

The two coacting offset or transfer cylinders are denoted by I and 2, each cylinder acting as an impression or pressure cylinder for the other. The web 3 is passed between the offset cylinders and around suitable guide rollers 4. The ofiset cylinders may be provided with any well known or approved surfaces capable of receiving the moistening agent and the'ink designs and transferring the same to both sides of the traveling web as it passes between the said offset cylinders.

The two color printing cylinders 5 and 6 are arranged to coact with the offset cylinder I to successively apply the ink designs thereto, their inking units being denoted by I and II respectively.

The two color printing cylinders 9 and II) are arranged to coact with the offset cylinder 2 to successively apply the ink designs thereto, their inking units being denoted by H and I2 respectively. The dampening cylinder I3 of the dampening unit I4 for applying the moisture directly to the offset cylinder I is shown in position to IV of Fig. 2. looking in the direction of the arrow;

Fig. 5 represents a detail view of one of the first printing cylinders taken in the plane of the line V-V of Fig. 2. looking in the direction of the arrows;

Fig. 6 represents a similar view of the other first printing cylinder taken in the plane of the line VI-VI of Fig. 2, looking in the direction of the arrows;

Fig. 7 represents a similar view of one of the second printing cylinders taken in the plane of the line VII of Fig. 2, looking in the direction of the arrow; and

transfer its moistening agent directly to the surface of the said offset cylinder I at a point between the web and the printing cylinder 5 so that the surface of the offset cylinder may be continuously moistened before it reaches the printing cylinders 5 and 6.

The dampening cylinder I5 of the dampening unit l6 for applying the moisture directly to the ofiset cylinder is shown in position to transfer its moistening agent directly to the surface of the said offset cylinder 2 at a point between the web and the printing cylinder 9 so that the surface of the offset cylinder 2 may be continuously moistened before it reaches the printing cylinders 9 and III.

In Figs. 2 to 8 inclusive the dampening cylinders I3 and I5 are "shown as provided with raised moisture carrying surfaces or designs I1 and II for transferring the moisture directly to the areas of their offset cylinders which are not to receive the ink designs from the printing cylinders. In these figures the printing cylinders 5, 6 and 9, II are shown as being provided with raised ink carrying surfaces I9, 20 and 2I, 22, each pair of raised surfaces being so related to each other and to their respective raised moisture carrying surfaces I! and I8 as to transfer the ink to those areas of the dampening cylinders which have not been moistened by the raised moisture carrying surfaces I1 and I8.

As a preliminary step to the web perfecting oii'set printing operation, offset developing inks may be applied to the printing cylinders and transferred thereby to their respective offset cylinders until the designs have been created thereon. The moistening agent may then be applied to the offset cylinders to maintain the design contours. Theoffset printing on the web may then be started.

As the printing operation proceeds the oifset cylinders are moistened and then the color printing cylinders act successively to apply the ink designs to their respective oflset cylinders. The offset cylinders will then simultaneously transfer. the ink designs successively received from the several printing cylinders to both sides of the traveling web. This operation is repeated each revolution of the offset cylinders.

It will be understood that when the dampening cylinders are provided with raised moisture carrying surfaces and the printing cylinders with raised ink design carrying surfaces the moisture and the colors are transferred to the offset cylinders so as to form continuous surfaces thereon consisting of separate moisture carrying and ink carrying areas to be transferred to both sides of the web by the said oifset cylinders.

When the moisture carrying surfaces of the dampening areas are smooth the moisture carried thereby is applied uninterruptedly to the entire surfaces of the offset cylinders instead of only to predetermined areas thereof. However, as the inks of the ink carrying areas of the oil'set cylinders are moisture repelling, due to the initially applied developing ink, no moisture will be transferred to these areas.

While I have shown in the accompanying drawings two printing cylinders for applying color designs or patterns to different offset cylinders to be transferred thereby to the traveling web, it is to be understood that any number of printingcylinders may be used without departing from the spirit, and scope of my invention.

It will also be understood that the circumference of the oifset cylinders must be an exact multiple of the circumference of the printing cylinders in order to make the design of these printing cylinders fit the circumference of their offset cylinders. In the present instance the circumference of the offset cylinders is shown as four times the circumference of the printing cylinders.

It will also be understood that the ink carrying surfaces of the printing cylinders may be of any well known or approved form.

It will furthermore be seen that by printing both sides of the web simultaneously from the offset cylinders, perfectly registered oil'set printing is obtained.

It is evident that various changes may be resorted to in the construction, form and arrangement of the several parts without departing from the spirit and scope of my invention, and hence I do not intend to be limited to the particular embodiment herein shown and described, but what I claim is:

1. In a multicolor web perfecting oflset rotary printing press, two coacting offset cylinders, means for passing the web therebetween, dampening cylinders having raised moisture carrying surfaces for applying moisture directly to said offset cylinders, a plurality of color printing cylinders arranged around each of the offset cylinders, said color printing cylinders having raised ink carrying surfaces, and means for applying ink thereto for successive transfer to their respective offset cylinders, the circumference of the offset cylinders being a multiple of the circumference of the dampening cylinders and of the inking cylinders, the said raised mois ture and ink carrying surfaces being positioned to produce continuous films on the offset cylinders consisting of separate moistened and inked areas to be transferred simultaneously to both sides of the web.

2. In a web perfecting offset rotary printing press, two coacting offset cylinders, means for passing the web therebetween, two dampening cylinders having raised moisture carrying surfaces, means for applying the moisture thereto for transfer to predetermined areas of the surfaces of their respective offset cylinders, two printing cylinders having complementary raised ink carrying surfaces, means for applying ink thereto for transfer to the unmoistened areas of their respective ofiset cylinders to produce continuous films on the oil'set cylinders consisting of separate moistened and inked areas, the circumference of the offset cylinders being a multiple of the circumference of the dampening cylinders and of the inking cylinders, and means for transferring the ink designs from said offset cylinders to both sides of the web.

HANS J. LUEHRS.

' REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 565,891 Frauenfelder Aug. 18, 1896 1,025,258 'Firm May 7, 1912 1,554,597 Rowles Sept. 22, 1925 1,698,544 Hicks Jan. 8, 1929 2,316,708 Ormond Apr. 13, 1943 FOREIGN PATENTS Number Country Date 198,092 Great Britain May 31, 1923 568,825 France Apr. 2, 1924 222,993 Great Britain Oct. 16, 1924 649,280 Germany Aug. 20, 1937 

